In the manufacture of steel rod, it has been common practice to form the basic steel ingot into a billet having a square cross-section with dimensions, for instance, of 4".times.4" and to allow the billet to cool for storage. The billet is subsequently taken from storage, heated in a reheat furnace and then presented to a multi-stand rod mill. The rod leaves the mill and is formed into coils for storage and/or sale. More specifically, the rod leaves the mill and is water-cooled on its way to the reel which forms the coil. By the time that the rod leaves the reel, it has regained most of its original temperature. Since the rod must be manipulated in order to be removed from the area, it is necessary to cool it; more importantly, however, it is imperative that this cooling take place in a certain manner in order to obtain desired metallurgical properties. For the purpose of such cooling, use has been made in the past of water or molten lead baths, but these systems have presented other unsolvable problems. Subsequently, a system known as the "STELMOR SYSTEM" was developed by the Morgan Construction Company of Worcester, Mass. This system consists of removing the hot rod from the reel in the form of spaced coils that are moved along a conveyor. Handling equipment is located at the located under the conveyor and are subjected to air flow from fans remote discharge end of the conveyor to re-form the coils and move successive coils to another location. With this system, it is possible to regulate the rate of cooling by adjusting fan speed and, on occasion, by providing a cover over the conveyor and coils.
While this system has proved to be adequate for ordinary steel rod, it has some drawbacks, particularly in the case where the rod is formed from alloy steels or when special metallurgical characteristics are desired. Since the rod is usually subjected to further manufacturing processes, such as drawing to form wire or used in header machines to make bolts, the physical character of the finished rod can be quite important. The presence of carbide boundaries in the steel can make it difficult to draw and may damage the dies. The presence of scale can also make the rod difficult to handle and to work.
Attempts have been made in the past to improve the flexibility of the conveyor-type cooling system. For instance, the U.S. patent of JALIL et al U.S. Pat. No. 4,448,401 and its associated U.S. Pat. No. 4,546,957 show a conveyor configuration in which the coils of rod are carried on hollow rollers and the cooling air is directed around the rollers. The patent of JALIL et al U.S. Pat. No. 4,580,353 relates to a roller-type conveyor in which the air is directed upwardly by a special nozzle arrangement. At one time, a system was suggested by Ashlow Engineering Limited of Sheffield, England, in which air has been provided under all parts of the conveyor, including the part under the reel, by a large number of small axial-flow fans, thus giving a certain amount of control of the quantity of air supplied at various parts of the conveyor. All of these systems have presented problems, including the high cost of the equipment and of being limited to use with ordinary steel rod. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a rod cooling system which uses a short conveyor, with subsequent reduction of equipment and building cost.
Another object of this invention is the provision of a rod cooling system that permits the production of favorable metallurgical characteristics in special alloy steels.
A further object of the present invention is the provision of apparatus for the controlled cooling of steel rod, which apparatus operates in such a way as to reduce the formation of carbide inclusions and of scale on the outer surface.
A still further object of the invention is the provision of a rod cooling apparatus that can be applied effectively to existing installations in order to provide faster or adequate cooling without lengthening the conveyor.
It is a further object of the invention to provide a rod cooling apparatus which is simple and rugged in construction, which can be easily manufactured from readily-obtainable materials, and which is capable of a long life of useful service with a minimum of maintenance.
Another object of the invention is the provision of a rod cooling system which can be used with a considerable variety of steel rod with different metallurgical characteristics.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.